Sunday, June 27, 2004
It takes a while to track down multiple credible primary source of information on this, however I can the results are in. As posted earlier, I was looking for the data on what seems to have become somewhat of a perpetual debate about the energy payback of solar panels.
The preconception of some people, from both advocacy and opposition camp on renewables is the basic premise that ?A solar panel won?t convert over it?s lifetime, he amount of useable energy from sunlight, that it takes in useable energy from fossil fuel to manufacture it in the first place?. The statement does seem to pass right through most people ?bullshitometer? and lodge in their squarely in their conciseness to be used in as counterpoints in polite debate about the environment and what we ?should? be doing.
The notion is a good fit for most people?s sense of what solar can a do, known as the ?little trickle of not much energy from the sun? theory of solar panel as like to call it. At the time of writing this, it seems that this is the prevailing view on solar.
Okay, now for the meat in the sandwich. The most common ?off-the-shelf? panels in circulation today (to the exclusion of laboratory prototypes and pre-commercialised products, my focus was just what mum and dad by buy at their nearest solar retailer) are based on 3 basic constructs, these are mono-crystalline, poly-crystalline and the most efficient (and expensive) amorphous or non-crystalline silicon construct. Let?s look at each.
Amorphous (non-crystalline) cells are made as a thin film layered on various (even flexible) substrates. These cells have a higher cost, lower efficiency (5.5% to 7.5%) and shorter warranty than the others do. The thin-film technology does allow the cells to be used in building-integrated products, such as the shingle style roof tiles made by Uni-Solar.
Multi-crystalline cells are easier to manufacture, but also slightly less efficient (11% to 14%) than mono-crystalline due to a lower-grade silicon. The warranty is similar to that of single crystalline. Prices for both single- and multi-crystalline cells are around $5.50 per watt generated; generally, multi-crystalline costs slightly less.
Single crystalline cells are most efficient at solar conversion (12% to 15% conversion to electricity) and carry the longest warranty (usually 25 years) for tested technology.
In evaluating the energy payback of any of these types of solar panel I am using this principle: Energy Payback = Usable Energy Output less Input Energy (Which includes the energy requirement for manufacturing, installation, energy use during operation, and energy needed for decommissioning at the product?s end of life). Variable in efficiency between different model panels and the climate and available sunlight at the installation site will vary the amount of energy output. The manufacturing process used will vary the amount of energy used to create the panel. Therefore, our results will be a range (favourable case scenario to unfavourable case scenario and disregarding the best & worst case, as these will be a very small percentage of installations in real terms) rather than one specific quantity.
Amorphous (non-crystalline) thin film solar panels can be, and often are used without a aluminium/steel frame and glass sheet over the top. Therefore they weather faster (shorter warranty) but have substantially less embodies energy than the poly and mono-crystalline panels we are all most used to seeing. For this reason alone, even with a lower efficiency these cells do provide energy payback. A range of 12 months to 3.0 years could be expected.
Poly & Multi-crystalline panels are made up multiple cells that are under glass, frame & sealed. They require a frame and glass to protect them from the elements, and use a lot of silicon but have much higher efficiency rates. A energy payback over a range of 2.0 to 4.0 years can be expected.
So clearly the myth that "it takes more electricity to manufacture a solar panel than it will ever put out." is simply not true... All current solar panels provide an energy payback.
This myth may have started during the Ronald Reagan era and it should die with him. Just some background ? Over twenty years ago Ronald Reagan tore Jimmy Carter's solar water heater from the White House roof and then took away tax credits for renewable energy, the solar-energy industry plummeted faster than the April 2000 tech-reck. All this came as no surprise as solar energy had been in Reagan?s sights since well before his Announcement for the Presidency speech in November 1979 when he stated a preference for another 20-30 of fossil fuel dependence rather that the 20% renewable energy by the year 2000 set target set down by Jimmy Carter in response to the 1970 oil crisis. Subsequent legislation to pass the American congress under Reagan stripped $600million dollars from the program and later removed federalised funding altogether. The fossil fuel lobby has finance the politicians ever since.
globalism 2:58 AM - [Link]
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globalism 2:57 AM - [Link]
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Now I recognise from the outset that I am going to have to go to gut at some point in the following article. I say this as I am full cognisant of the fact that more eminent people that myself hold contrary views on the subject, and that said I intend to find a definitive position. So what is all the fuss about? Well it touches on two of my main blogging themes ? technology & environment. The issue I want to confront: Does it take more energy to product a solar panel that that panel will produce (convert from sunlight) in it?s working life?? Or put in reverse: Does a solar panel produce (convert from sunlight) more energy in it?s working life than it takes (presumably, as is mostly the case, from fossil fuel ? Coal, Gas, Petrol) to manufacture?
To tackle this question I start by limiting my scope to panels which are available from Kyocera or BP Solar today ? off the shelf ? and not what might be in development ? in a lab ? or otherwise not representative of the marketplace. Secondly I declare at the outset I have a gut feeling that solar panels do in fact produce (convert from sunlight) more usable energy than they require to produce over their working life so I will now seek out the numbers on the net.. Sighting sources and email key researchers that may assist me in finding the answer to this vexing issue.
globalism 2:49 AM - [Link]
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